This attribute controls how a TimeFrame behaves when it is used (by
astFindFrame or astConvert) as a template to match another (target)
TimeFrame. It identifies the time scale in which alignment is
to occur. See the TimeScale attribute for a desription of the values
which may be assigned to this attribute. The default AlignTimeScale
value depends on the current value of TimeScale: if TimeScale is
UT1, GMST, LMST or LAST, the default for AlignTimeScale is UT1, for all
other TimeScales the default is TAI.
When astFindFrame or astConvert is used on two TimeFrames (potentially
describing different time coordinate systems), it returns a Mapping
which can be used to transform a position in one TimeFrame into the
corresponding position in the other. The Mapping is made up of the
following steps in the indicated order:
- Map values from the system used by the target (MJD, JD, etc) to the
system specified by the AlignSystem attribute.
- Map these values from the target's time scale to the time scale
specified by the AlignTimeScale attribute.
- Map these values from the time scale specified by the AlignTimeScale
attribute, to the template's time scale.
- Map these values from the system specified by the AlignSystem
attribute, to the system used by the template.